Survey system

ABSTRACT

A survey system including a movable photographing device, a surveying device, and an analysis device. The movable photographing device includes a camera mounted on a UAV and taking a plurality of images P for photogrammetry, and a GPS unit including a first time stamping portion stamping a first time Tc relating to a photographing time on the image P taken. The surveying device determines a position of the movable photographing device, and includes a second time stamping portion stamping a second time Tt relating to a surveying time on a survey result R determined above. The analysis device includes a photographing position analysis portion associating each survey result R with a photographing position of the respective image P based on the first time Tc and the second time Tt, and generating data for photogrammetry.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2017-022471 filed on Feb. 9, 2017, the entire disclosure of which isincorporated by reference herein.

BACKGROUND

The present disclosure relates to a photogrammetry system that includesa movable photographing device taking images for photogrammetry and asurveying device determining a position of the movable photographingdevice.

In typically known stereophotogrammetry, a movable body includes acamera, which takes images (static images and dynamic images) from twoor more different positions, the images being used for a survey.

In particular, in recent photogrammetry, a UAV (Unmanned Air Vehicle) isused as a movable body including a camera, which takes images from thesky.

In such photogrammetry, it has been necessary to take an image so that aplurality of control points are photographed in the image, in order toassociate the image with a ground point. As such, the photographingoperation has been limited. It has been also necessary to take effort toset air marks indicative of the control points in a target survey areain advance so that the control points are clearly photographed in theimage taken.

To address this problem, Japanese Unexamined Patent Publication No.2015-145784 discloses photogrammetry where positional information of aUAV is obtained from a GPS and a total station (a position measurementdevice) to take images for photogrammetry at positions predetermined ina flight plan. As such, the GPS and the total station are used toidentify the photographing positions so that the number of controlpoints required in the image can be reduced, or the step of associatingthe control points can be omitted.

SUMMARY OF THE EMBODIMENTS

However, in the photogrammetry of Japanese Unexamined Patent PublicationNo. 2015-145784, the position, determined by the GPS, of the UAV duringa photographing operation is less accurate than the position, determinedby the total station, of the UAV.

On the contrary, when the position of the UAV is determined by the totalstation, the total station is away from the camera of the UAV during aphotographing operation. Thus, the total station cannot recognize thetime when the camera of the UAV conducts an actual photographingoperation. Then, a time difference occurs between the photographing timeand the surveying time so that the photographing position is identifiedless accurately.

In view of the foregoing, it is an object of the present disclosure toprovide a survey system capable of precisely associating a photographingtime of an image taken by a movable photographing device including amovable body (such as a UAV) and a camera with a surveying time obtainedby a surveying device such as a total station, to accurately identify aphotographing position to improve the accuracy of photogrammetry.

To achieve the object, the survey system of an embodiment of the presentdisclosure includes a movable photographing device including a movablebody, a photographing portion taking a plurality of images forphotogrammetry, and a first time stamping portion stamping a first timerelating to a photographing time on the images taken by thephotographing portion; a surveying device including a surveying portiondetermining a position of the movable photographing device, and a secondtime stamping portion stamping a second time relating to a surveyingtime on a survey result obtained by the surveying portion; and aphotographing position analysis portion associating, based on the firsttime and the second time, a survey result obtained by the surveyingdevice with a photographing position of each image taken by the movablephotographing device, and generating data for photogrammetry.

An embodiment of the present disclosure containing the aboveconfiguration can provide associating a photographing time of an imagetaken by a movable photographing device including a movable body and acamera with a surveying time obtained by a surveying device, toaccurately identify a photographing position to improve the accuracy ofphotogrammetry.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall configuration diagram of a survey system of oneembodiment of the present disclosure.

FIG. 2 is a control block diagram of the survey system of one embodimentof the present disclosure.

FIG. 3 is a time chart of photographing and surveying conducted by thesurvey system of this embodiment of the present disclosure.

FIG. 4 is a control block diagram of a survey system of a variation ofthe present disclosure.

FIG. 5 is a time chart of photographing and surveying conducted by thesurvey system of the variation.

FIG. 6 shows an example of time measurement in a case where a GPS signalis blocked.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described below withreference to the drawings.

FIG. 1 is an overall configuration diagram of a survey system 1 of oneembodiment of the present disclosure. FIG. 2 is a control block diagramof the survey system 1. The overall configuration and control system ofthe survey system 1 of the embodiment of the present disclosure will bedescribed with reference to FIGS. 1 and 2.

The survey system 1 is a survey system for photogrammetry. The surveysystem 1 includes a movable photographing device 2 moving to take aplurality of images for photogrammetry, a surveying device 3 determininga position of the movable photographing device 2, and an analysis device4 analyzing a photographing result and a surveying result and generatingdata for photogrammetry.

The movable photographing device 2 is composed of a UAV 10, which is amovable body. The UAV 10 includes a camera 11 (a photographing portion)taking images for photogrammetry. Note that the image taken by thecamera 11 may be a static image or a dynamic image.

Specifically, the UAV 10 is a flight movable body capable of flyingthrough a predetermined flight path and freely flying by remote control.The UAV 10 includes a flight mechanism 10 a for flight and a gimbalmechanism 10 b provided below the flight mechanism 10 a.

The camera 11 is supported by the gimbal mechanism 10 b of the UAV 10.The gimbal mechanism 10 b enables the camera 11 to take images in anydirection, and allows the camera 11 to have a stabilized attitude totake images in a fixed direction.

The camera 11 has a body having a front surface provided with a lensportion 12. The lens portion 12 has a front end beside which a prism 13is provided. The camera 11 is also provided with a GPS unit 14 capableof receiving a GPS signal.

The surveying device 3 is a total station capable of automaticallytracking a survey object. The surveying device 3 includes a horizontallyrolling portion 30 capable of rolling in a horizontal direction, avertically rolling portion 31 capable of rolling in a verticaldirection, and a telescope portion 32 provided on the horizontallyrolling portion 30 through the vertically rolling portion 31. Thetelescope portion 32 is also provided with an electro-optical distancemeter (EDM) 33 (a surveying portion) measuring a slant distance to atarget.

Specifically, the surveying device 3 can perform prism survey forsurveying the prism 13. That is, the surveying device 3 can measure adistance from the surveying device 3 to the prism 13, and also canmeasure a horizontal angle and a vertical angle formed by the surveyingdevice 3 and the prism 13. Thus, the surveying device 3 arranged in apredetermined position and having an attitude in a leveled manner cansurvey the prism 13 to calculate coordinates of the prism 13, i.e., aposition of the camera 11, based on the survey results (the slantdistance, the horizontal angle, and the vertical angle).

The analysis device 4 is an information processing terminal such as apersonal computer capable of associating a survey result obtained fromthe surveying device 3 with a photographing position where each imagehas been taken by the movable photographing device 2, and generatingdata for photogrammetry.

In the survey system 1, as illustrated in FIG. 1, the movablephotographing device 2 moves in the sky to take a plurality of imagesP1, P2, . . . , Pn for photogrammetry by a predetermined photographingperiod ΔS. Then, the surveying device 3 tracks and surveys the movablephotographing device 2 (strictly, the prism 13) to conduct a survey.Then, the analysis device 4 associates the images P1, P2, . . . , Pntaken by the movable photographing device 2 with survey results R1, R2,. . . , Rm obtained by the surveying device 3, and then generates datafor photogrammetry.

Next, referring to FIG. 2, the configuration of the control system basedon the camera 11, the surveying device 3, and the computer of theanalysis device 4, of the survey system 1, will be described.

As illustrated in FIG. 2, the camera 11 includes a photographing controlportion 15. The photographing control portion 15 is electricallyconnected with a communication portion 16, an operating portion 17, animaging portion 18, and a strobe signal terminal 19. Note that, althoughnot shown, the photographing control portion 15 may also be connectedwith a memory portion, a display portion, etc., and may be connectedwith a sensor etc. At least images taken are stored in an internal orexternal memory portion.

The communication portion 16 can communicate with exterior equipment.The communication portion 16 is, e.g., a wireless communication meanssuch as a Bluetooth (a registered trademark). Note that, thecommunication portion 16 may include a wired communication means thougha connecting terminal. This also applies to the following communicationportion.

The operating portion 17 is a control means for inputting variousoperational instructions or settings to the photographing controlportion 15. Examples of the operational instructions includeinstructions for turning on or off a power supply, triggering aphotographing operation, switching a photographing mode, setting aphotographing period, setting an image quality, and turning on or off aconnection with the surveying device 3. The operating portion 17 mayalso include any operating or input devices such as switches, buttons,and dials.

The imaging portion 18 performs a photographing operation. The imagingportion 18 includes an imaging device (such as a CCD and a CMOS device)converting an optical image into electrical signals, and a shutter.

The strobe signal terminal 19 is, e.g., a hot shoe or a synchro terminalfor a strobe. The strobe signal terminal 19 is a connecting terminalcapable of communicating a shutter signal to external equipment.

The photographing control portion 15 can control the imaging portion 18so that the imaging portion 18 performs a photographing operation by apredetermined photographing period ΔS. The photographing control portion15 can also make the strobe signal terminal 19 convey a shutter signalor a taken image to external equipment.

The GPS unit 14 is connected with the camera 11 through the strobesignal terminal 19. The GPS unit 14 includes a first time stampingportion 20 and a photographing memory portion 21.

The first time stamping portion 20 receives a GPS signal containing timeinformation from a GPS satellite. The first time stamping portion 20includes a clock. The clock generates a GPS time based on the GPSsignal. The clock generates a PPS signal which is a periodic pulse. Inresponse to the shutter signal conveyed through the strobe signalterminal 19, the first time stamping portion 20 stamps a first time Tc(a GPS time) relating to a photographing time on an image P taken by thecamera 11, and outputs the image P to the photographing memory portion21. Note that the GPS time is, e.g., an absolute time based onCoordinated Universal Time (UTC).

The photographing memory portion 21 can store the image data containingthe first time Tc that the first time stamping portion 20 stamped on theimage P taken by the camera 11.

The surveying device 3 includes a survey control portion 34 connectedwith the horizontally rolling portion 30, the vertically rolling portion31, and the EDM 33. The survey control portion 34 is also connected witha horizontal angle detection portion 35 (a surveying portion), avertical angle detection portion 36 (a surveying portion), a displayportion 37, an operating portion 38, a tracking light transmissionportion 39, a tracking light reception portion 40, a communicationportion 41, a second time stamping portion 42, and a survey memoryportion 43.

The horizontal angle detection portion 35 detects a rolling angle of thehorizontally rolling portion 30 in the horizontal direction to detect ahorizontal angle collimated by the telescope portion 32. The verticalangle detection portion 36 detects a rolling angle of the verticallyrolling portion 31 in the vertical direction to detect a vertical anglecollimated by the telescope portion 32. From the horizontal angledetection portion 35 and the vertical angle detection portion 36, ahorizontal angle and a vertical angle as survey results are detected.

The display portion 37 is, e.g., a liquid crystal monitor. The displayportion 37 can display various pieces of information such as the surveyresults (the slant distance, the horizontal angle, the vertical angle).

The operating portion 38 is a control means for inputting variousoperational instructions or settings to the survey control portion 34.Examples of the operational instructions include instructions forturning on or off a power supply, triggering a survey, switching asurvey mode, and setting a surveying period. Similarly to the operatingportion of the camera 11, the operating portion 38 may include anyoperating or input devices such as switches, buttons, and dials.

The tracking light transmission portion 39 emits track light. Thetracking light reception portion 40 receives the tracking lightreflected by the prism 13. The survey control portion 34 controls thehorizontally rolling portion 30 and the vertically rolling portion 31 toenable the tracking light reception portion 40 to keep receiving thetracking light from the tracking light transmission portion 39. As such,the function of tracking a target is achieved.

Similarly to the communication portion 16 of the camera 11, thecommunication portion 41 can communicate with exterior equipment. Thecommunication portion 41 is, e.g., a wireless communication means suchas a Bluetooth.

Similarly to the first time stamping portion 20, the second timestamping portion 42 receives a GPS signal containing time informationfrom a GPS satellite. The first time stamping portion 20 includes aclock. The clock generates a GPS time based on the GPS signal. The clockgenerates a PPS signal which is a periodic pulse. In response toconduction of a survey, the second time stamping portion 42 stamps asecond time Tt (a GPS time) relating to a surveying time on a surveyresult R, and outputs the survey result R to the survey memory portion43.

The survey memory portion 43 can store a program for the above-describedtracking function; various programs for survey (e.g., a program forconducting a survey by a predetermined surveying period); and variouspieces of data (e.g., survey data containing the second time Tt stampedon the survey result R by the second time stamping portion 42).

The survey control portion 34 starts a survey by a predeterminedsurveying period ΔT when tracking of the prism 13 starts. Then, thesurvey memory portion 43 stores the survey data containing the secondtime Tt stamped on the survey result R by the second time stampingportion 42.

The analysis device 4 includes a photographing position analysis portion50. The photographing position analysis portion 50 can be connected in awired or wireless manner with the movable photographing device 2 and thesurveying device 3. The photographing position analysis portion 50obtains each image data containing the image P on which the first timeTc was stamped and which is stored in the photographing memory portion21 of the movable photographing device 2. The photographing positionanalysis portion 50 also obtains the survey data containing the surveyresult R on which the second time Tt was stamped and which is stored inthe survey memory portion 43 of the surveying device 3. Then, thephotographing position analysis portion 50 associates the image datewith the survey data based on the first time Tc and the second time Ttto generate the data for photogrammetry.

Here, FIG. 3 is a time chart of photographing and surveying conducted bythe survey system of this embodiment. A methodology of generation of thedata for photogrammetry of the survey system will be described belowwith reference to FIG. 3.

The movable photographing device 2 flies along a flight plan, andconducts photographing operations a plurality of times (n times) throughthe camera 11 by a predetermined photographing period ΔS. When thephotographing operations are performed through the camera 11, inresponse to the shutter signal, the first time stamping portion 20 ofthe GPS unit 14 stamps the first time Tc relating to the photographingtime on the image P, and the photographing memory portion 21 stores theimage P. For example, in FIG. 3, a first time Tc1 is stamped on an imageP1 taken in a first photographing operation. Another first time Tc2 isstamped on an image P2 taken in a second photographing operation.Another first time Tcn is stamped on an image Pn taken in an n^(th)photographing operation.

On the other hand, the surveying device 3 tracks the movablephotographing device 2, and determines a position of the camera 11 by apredetermined surveying period ΔT. Note that the surveying period ΔT isa shorter period (a high frequency) than the photographing period ΔS.For example, a survey is conducted by the surveying period ΔT=20 ms to100 ms with respect to the photographing period ΔS=1 s to 3 s. In FIG.3, the surveying period ΔT is a tenth of the photographing period ΔS forthe sake of convenience of illustration.

Then, in the surveying device 3, for every survey, a second time Ttcorresponding to a surveying time of the survey result R (the slantdistance, the horizontal angle, the vertical angle) is stamped, andstored in the survey memory portion 43.

For example, in FIG. 3, a second time Tt3 is stamped on a third surveyresult R3 counted from the start of tracking. Another second time Tt13is stamped on a thirteenth survey result R13. Another second time Ttm isstamped on an m^(th) survey result Rm.

After the movable photographing device 2 completes all the photographingoperations, the photographing position analysis portion 50 of theanalysis device 4 receives the image data each composed of the image Pand the first time Tc stored in the photographing memory portion 21, andthe survey data each composed of the survey result R and the second timeTt stored in the survey memory portion 43.

The photographing position analysis portion 50 extracts the surveyresult R containing the second time Tt matching the first time Tcstamped on the image P to associate the extracted survey result R withthe photographing position of the image P to generate the data forphotogrammetry.

For example, in FIG. 3, the first time Tc1 corresponding to the firstimage P1 matches the second time Tt3 corresponding to the survey resultR3. Thus, the survey result R3 is associated with a photographingposition of the image P1.

Note that, if the first time Tc does not match the second time Tt, asecond time Tta immediately before the first time Tc and a second timeTtb immediately after the first time Tc are designated as second timesmatching the first time Tc. Then, an interpolation survey result Ri iscalculated by interpolation of survey results Ra, Rb corresponding tothe second times Tta, Ttb, respectively. Then, the interpolation surveyresult Ri can be associated.

As described above, in the survey system 1 of this embodiment, themovable photographing device 2 and the surveying device 3 include thefirst time stamping portion 20 and the second time stamping portion 42,respectively, each capable of stamping a time with the same accuracy.The first time stamping portion 20 stamps the first time Tc on eachimage P taken by the camera 11. The second time stamping portion 42stamps a second time Tt on each survey result R obtained by thesurveying device 3. Then, in the analysis device 4, the survey result Ron which the second time Tt matching the first time Tc of each image Pwas stamped is associated so that the survey result R precisely surveyedby the surveying device 3 is associated with a photographing position ofthe image P. Then, the data for photogrammetry can be generated.Accordingly, an exact photographing position is identified, and a moreaccurate photogrammetry can be achieved.

In particular, the first time stamping portion 20 and the second timestamping portion 42 each include a clock measuring time based on the GPSsignal to securely and precisely stamp the first time Tc and the secondtime Tt, respectively. Thus, the survey system of this embodiment can beused in the world.

The descriptions of one embodiment of the present invention is nowended. However, the aspect of the present invention is not limited tothis embodiment.

For example, in the embodiment described above, the surveying device 3conducts surveys by the predetermined surveying period ΔT to obtain thesurvey results R, and the survey memory portion 43 stores all the surveyresults R obtained. To store a less amount of information, the surveymemory portion 43 may store only necessary ones of the survey results Rextracted during a photographing operation of the movable photographingdevice 2.

Specifically, a variation of the embodiment will be described withreference to FIGS. 4 and 5. FIG. 4 is a control block diagram of asurvey system of the variation. FIG. 5 is a time chart of photographingand surveying conducted by the survey system of the variation. Thevariation will be described below with reference to the drawing. Notethat the same configurations as those of the embodiment described aboveare labeled with the same reference characters. The detaileddescriptions thereof will be omitted.

In a survey system 1′ of the variation, a surveying device 3′ includes asurvey control portion 34′ that also has a function of the photographingposition analysis portion 50 of the embodiment described above. In thesurvey system 1′, the information about a first time Tc stamped on ataken image P is sent to the surveying device 3′ through a communicationportion 16 of a camera 11 and a communication portion 41 of thesurveying device 3′ every time the camera 11 takes a photograph.

Specifically, for example, as illustrated FIG. 5, when a first time Tc1is stamped on an image P1 taken in a first photographing operation, theinformation about the first time Tc1 is simultaneously sent to thesurveying device 3′. Similarly, in a second photographing operation, afirst time Tc2 relating to an image P2 is sent to the surveying device3′. This also applies to a third and later photographing operations.

The surveying device 3′ conducts a survey by a predetermined surveyingperiod ΔT, and the survey control portion 34′ makes the survey memoryportion 43 temporarily store the survey result R thereof. When thesurveying device 3′ receives the information about the first time Tc,the survey control portion 34′ makes the survey memory portion 43 holdonly the survey result R containing a stamp of a second time Tt matchingthe first time Tc.

For example, in FIG. 5, suppose that the photographing time does notmatch the surveying time. Then, when the surveying device 3′ receives afirst time Tc1 relating to a first image P1, the survey memory portion43 holds survey results R2, R3 corresponding to a second time Tt2immediately before the first time Tc1 and a second time Tt3 immediatelyafter the first time Tc1, respectively. In other words, the surveycontrol portion 34′ makes the survey memory portion 43 delete the surveyresult R1 obtained before the survey results R2, R3 corresponding to thesecond times Tt2, Tt3.

Similarly, when a first time Tc2 is stamped on an image P2 taken in asecond photographing operation, the information about the first time Tc2is simultaneously sent to the surveying device 3′. Then, the surveycontrol portion 34′ makes the survey memory portion 43 hold the surveyresults R12, R13 containing second times Tt12, Tt13 matching the firsttime Tc2. The survey control portion 34′ also makes the survey memoryportion 43 delete survey results R4 to R11 containing second times Tt4to Tt11 not matching the first time Tc. This also applies to a third andlater photographing operations.

Then, during photographing operations or after all the photographingoperations conducted by the movable photographing device 2, the surveycontrol portion 34′ calculates interpolation survey results Ri23, Ri1213through interpolation of the survey results R2, R3, R12, R13, toassociate the interpolation survey results Ri23, Ri1213 with the imagesP1, P2 to obtain the data for photogrammetry.

In particular, if associating the survey result R with the image Pduring a photographing operation conducted by the movable photographingdevice, the survey control portion 34′ may make the display portion 37display the generated data for photogrammetry. Accordingly, an exactposition of the movable photographing device 2 can be checked during aphotographing operation conducted by the movable photographing device 2,and also the flight plan can be confirmed or revised during aphotographing operation conducted by the movable flight of photographingdevice 2 in flight.

As described above, in the survey system 1′ of the variation, the surveymemory portion 43 holds only the survey result R matching the first timeTc stamped on the image P. Thus, in the surveying device 3′, unnecessarysurvey results R can be reduced, and the data can be output withoutredundancy.

In the embodiment and variation described above, the movablephotographing device 2 is composed of the UAV 10 as a movable body.However, the movable body is not limited thereto, and may be a movablebody moving on the ground, such as a vehicle or a human.

In the embodiment described above, the camera 11 is connected with theGPS unit 14 through the strobe signal terminal 19. However, the cameramay internally include the GPS unit.

In the embodiment described above, the first time stamping portion 20and the second time stamping portion 42 use the respective clocksmeasuring time based on the GPS signals to stamp the first time Tc andthe second time Tt, respectively. However, the clocks used by the firstand second time stamping portions only have to be capable of measuringtime with the same accuracy, and may be, e.g., so-called radio clockscapable of receiving standard radio waves to correct a time difference.

Suppose that, due to influence by a surrounding building or reduction inthe number of satellites observed, the GPS signal is temporarily blockedfrom the first and second time stamping portions. In this case, a CPUclocking means (e.g., a timer counter composed of a crystal oscillator)contained in the photographing control portion, the survey controlportion, the first time stamping portion, or the second time stampingportion may be complementary to measurement of the first time and thesecond time.

Note that the CPU timer counter might be slightly affected by, e.g., atemperature. Thus, for example, as illustrated in FIG. 6, a PPS signalof one second period is preferably measured and studied by the CPU timercounter so that, if the GPS signal is blocked, the latest counter timeC(n) is used to measure the first time and the second time. In otherwords, even in the case of failure in receiving the GPS signals, the PPSsignal is considered to be received at the time when the CPU timercounter shows that the counter time C(n) has passed. Then, the time ismeasured.

Thus, even if the GPS signal cannot be temporarily received, the firsttime and the second time can be stamped accurately, and the accuracy ofphotogrammetry can be maintained.

What is claimed is:
 1. A survey system comprising: a movablephotographing device including a movable body, a photographing portiontaking a plurality of images for photogrammetry, and a first timestamping portion stamping a first time relating to a photographing timeon the images taken by the photographing portion; a surveying deviceincluding a surveying portion determining a position of the movablephotographing device, and a second time stamping portion stamping asecond time relating to a surveying time on a survey result obtained bythe surveying portion; and a photographing position analysis portionassociating, based on the first time and the second time, a surveyresult obtained by the surveying device with a photographing position ofeach image taken by the movable photographing device, and generatingdata for photogrammetry.
 2. The survey system of claim 1, wherein thesurveying portion of the surveying device tracks the movablephotographing device, and determines a position of the movablephotographing device by a predetermined surveying period shorter than aninterval between photographing operations conducted by the photographingportion; and after the movable photographing device completes all thephotographing operations, the photographing position analysis portionobtains, from the movable photographing device, each image on which thefirst time is stamped, and obtains, from the surveying device, eachsurvey result on which the second time is stamped, associates the surveyresult on which the second time matching the first time is stamped withthe respective image, and generating data for photogrammetry.
 3. Thesurvey system of claim 1, wherein the movable photographing deviceincludes a communication portion capable of communicating with thesurveying device, and sends information about the first time stamped onthe image through the communication portion every time the photographingportion conducts a photographing operation; and the surveying portion ofthe surveying device tracks the movable photographing device, anddetermines a position of the movable photographing device by apredetermined surveying period shorter than an interval betweenphotographing operations conducted by the photographing portion,receives the information about the first time, and holds only a surveyresult on which the second time matching the first time is stamped. 4.The survey system of claim 1, wherein the first time stamping portionand the second time stamping portion stamp the first time and the secondtime, respectively, with a clock measuring a time based on a GPS signal.